Worldsheet Scattering in AdS_5 x S^5

We calculate the S-matrix in the gauge-fixed sigma-model on AdS_5 x S^5 to the leading order in perturbation theory, and analyze how supersymmetry is realized on the scattering states. A mild nonlocality of the supercharges implies that their action on multi-particle states does not follow the Leibniz rule, which is replaced by a nontrivial coproduct. The plane wave symmetry algebra is thus naturally enhanced to a Hopf algebra. The scattering matrix elements obey the classical Yang-Baxter equation modified by the existence of the coproduct. This structure mirrors that of the large 't Hooft coupling expansion of the S-matrix for the spin chain in the dual super-Yang-Mills theory.Comment: 51 pages, v2: references added, v3: sign in (2.12), (6.19) and (6.21) corrected; v4: discussion of classical YBE is considerably modifie

On Symmetry Enhancement in the psu(1,1|2) Sector of N=4 SYM

Strong evidence indicates that the spectrum of planar anomalous dimensions of N=4 super Yang-Mills theory is given asymptotically by Bethe equations. A curious observation is that the Bethe equations for the psu(1,1|2) subsector lead to very large degeneracies of 2^M multiplets, which apparently do not follow from conventional integrable structures. In this article, we explain such degeneracies by constructing suitable conserved nonlocal generators acting on the spin chain. We propose that they generate a subalgebra of the loop algebra for the su(2) automorphism of psu(1,1|2). Then the degenerate multiplets of size 2^M transform in irreducible tensor products of M two-dimensional evaluation representations of the loop algebra.Comment: 35 pages, v2: references added, sign inconsistency resolved in (5.5,5.6), v3: Section 3.4 on Hamiltonian added, minor improvements, to appear in JHE

Three-Point Functions in N=4 SYM Theory at One-Loop

We analyze the one-loop correction to the three-point function coefficient of scalar primary operators in N=4 SYM theory. By applying constraints from the superconformal symmetry, we demonstrate that the type of Feynman diagrams that contribute depends on the choice of renormalization scheme. In the planar limit, explicit expressions for the correction are interpreted in terms of the hamiltonians of the associated integrable closed and open spin chains. This suggests that at least at one-loop, the planar conformal field theory is integrable with the anomalous dimensions and OPE coefficients both obtainable from integrable spin chain calculations. We also connect the planar results with similar structures found in closed string field theory.Comment: 34 pages, 9 figures, harvmac; references adde

Characterization of oral yeasts isolated from healthy individuals attended in different Colombian dental clinics

The aim of this study was to identify the most frequent yeasts in the oral cavity of adult individuals without immune disorders and to associate the presence of these oral yeasts with different characteristics of each individual. Oral rinse samples were obtained from 96 healthy adults and cultured in Sabouraud dextrose agar media and CHROMagar. Yeasts were identified by sequencing the D1/D2 region of the 28S rRNA gene. Probable association among the socio-demographic characteristics, body mass index, family and personal medical history, oral hygiene, tobacco and/or alcohol consumption habits and presence of oral fungi was analyzed. Contingency tables and logistic regression were employed to evaluate possible relationships between the presence of oral fungi and mixed colonization with these variables. 57.3% of the healthy individuals had oral yeasts and 21.8% had mixed colonization. The most prevalent yeasts were Candida albicans (52%), C. parapsilosis (17.9%), and C. dubliniensis (7.57%). Yeasts with most frequently mixed colonization were C. albicans and C. parapsilosis. No relationships were found among the variables analyzed. However, the presence of mixed colonization was related to the presence of dental prostheses (P less than 0.006), dental apparatuses (P=0.016) and O'Leary index (P=0.012). This is the first study that characterized oral yeasts in Colombian healthy individuals, determined the most prevalent oral yeasts C. albicans, C. parapsilosis and C. dublinensis and an association of mixed colonization with the use of dental prostheses and aparatology and poor hygiene. © 2019 by the Journal of Biomedical Research

Improved matrix-model calculation of the N=2 prepotential

We present a matrix-model expression for the sum of instanton contributions to the prepotential of an N=2 supersymmetric U(N) gauge theory, with matter in various representations. This expression is derived by combining the renormalization-group approach to the gauge theory prepotential with matrix-model methods. This result can be evaluated order-by-order in matrix-model perturbation theory to obtain the instanton corrections to the prepotential. We also show, using this expression, that the one-instanton prepotential assumes a universal form.Comment: 20 pages, LaTeX, 2 figure

On String S-matrix, Bound States and TBA

The study of finite J effects for the light-cone AdS superstring by means of the Thermodynamic Bethe Ansatz requires an understanding of a companion 2d theory which we call the mirror model. It is obtained from the original string model by the double Wick rotation. The S-matrices describing the scattering of physical excitations in the string and mirror models are related to each other by an analytic continuation. We show that the unitarity requirement for the mirror S-matrix fixes the S-matrices of both theories essentially uniquely. The resulting string S-matrix S(z_1,z_2) satisfies the generalized unitarity condition and, up to a scalar factor, is a meromorphic function on the elliptic curve associated to each variable z. The double Wick rotation is then accomplished by shifting the variables z by quarter of the imaginary period of the torus. We discuss the apparent bound states of the string and mirror models, and show that depending on a choice of the physical region there are one, two or 2^{M-1} solutions of the M-particle bound state equations sharing the same conserved charges. For very large but finite values of J, most of these solutions, however, exhibit various signs of pathological behavior. In particular, they might receive a finite J correction to their energy which is complex, or the energy correction might exceed corrections arising due to finite J modifications of the Bethe equations thus making the asymptotic Bethe ansatz inapplicable.Comment: 77 pages, 6 figures, v2: the statement about the periodicity condition for mirror fermions corrected; typos corrected; references added, v3: misprints correcte

Weakly coupled N=4 Super Yang-Mills and N=6 Chern-Simons theories from u(2|2) Yangian symmetry

In this paper we derive the universal R-matrix for the Yangian Y(u(2|2)), which is an abstract algebraic object leading to rational solutions of the Yang-Baxter equation on representations. We find that on the fundamental representation the universal R-matrix reduces to the standard rational R-matrix R = R_0(1 + P/u), where the scalar prefactor is surprisingly simple compared to prefactors one finds e.g. for sl(n) R-matrices. This leads precisely to the S-matrix giving the Bethe Ansatz of one-loop N = 4 Super Yang-Mills theory and two-loop N = 6 Chern-Simons theory.Comment: 16 page

Biometric differences between several populations of Cordulegaster boltonii (Odonata: Cordulegastridae) in Ibero-Maghrebian area

Biometric data of the exuviae of female larvae of the dragonfly Cordulegaster boltonii collected in Portugal, Spain and Morocco were analysed to determine whether the size of three exuvial structures measured differed depending on the geographic localities of the populations. Based on the results recorded for the 16 populations studied, head width was negatively correlated with latitude and the greatest length of the gonapophysis was recorded for the Iberian populations at the centre of this peninsula. Multivariate cluster analysis revealed a clear separation of the Moroccan population. A second cluster separated the southernmost population (Sierra Nevada) from the remaining Iberian populations. Four population groups were distinguished: those located in watercourses in the north and central area of the Iberian Peninsula, those in Iberian watercourses in the East and Middle South, the Sierra Nevada and North Morocco. Some of these results coincide with the results of genetic studies of other authors